After (far too) many months of reading about and handling various DSLRs, I’ve just about decided the Olympus E-510 is the right choice for me. I love the way it feels in my hands, and I love all but one of its features: the way the camera uses the pop-up flash instead of a dedicated AF assist lamp to assist the autofocus mechanism in low-light conditions. While this might be an effective way for the camera to achieve focus lock, there are just too many settings (such as museums, or photographing wildlife at twilight) where strobing the flash is simply out of the question. To me, this poses a very real limitation of the camera. I know manual focus is an option, but frankly I’m not sure how well my aging eyes will do focusing accurately under dim light situations.

I just learned, though, that at least two of Olympus’s external flash units, the FL-36 and FL-50, have built-in red AF assists lamps. From the reviews I’ve read, they significantly improve the ability of the E-510 to achieve focus lock in dim light, which sounds wonderful. There’s one question about these flash units I haven’t been able to find the answer to, though. Can the camera + external flash be configured in such a way that the camera will use the red AF assist lamp on the external flash to achieve focus lock, but NOT go on to take a flash photograph? If yes, then that would solve my problem nicely – I’ll pick up one of the external flash units when I buy the E-510, and go away a happy photographer.

The focus assist lamps have a limited range, shorter than the flash range. If you intend to shoot twilight photos at long distance it is likely better to manual focus. Another solution I have found effective is to use a small led flashlight. I bought one for about $6 at the local electronics emporium for that very use. I don’t believe the autofocus is sensitive to infrared light and so got a clear led light. It seems to work well up to about 30 ft. I would really like to find a small fitting to attach it to the hot shoe slot so I didn’t have to hold it but for $6 .. This method requires disabling the auto flash pop up in the menu.